Electrically heated hair-curling instrument

ABSTRACT

A hair-curling instrument embodies a heat conductive shell which is internally heated by an electric heating element and which is supported from a hollow handle by means of an arrangement which inhibits the transfer of heat from the heating element to the handle. A tubular rivet extending through an aperture in an end closure on the shell and an opening in the end of the handle holds the handle and shell in axial alignment. The heating element leads pass through the rivet. Thermally nonconductive spacers secured to the handle end and seated in recesses in the shell end closure are interposed between the shell closure and the handle end so as to define air gap between the confronting surfaces of the handle end and the closure member.

United States Patent 72] Inventor Samuel L. McNair Overland Park, Kans.[21] Appl. No. 726,620 [22] Filed May 3, 1968 [45] Patented May 18,1971[73] Assignee The Songrand Corporation Kansas City, Mo.

[54] ELECTRICALLY HEATED HAIR-CURLING INSTRUMENT 1 Claim, 6 DrawingFigs. [52] U.S. Cl 219/226, 16/116, 132/33, 219/227, 219/241, 219/531,219/533 [51] Int. Cl H45d 2/36, 1105b 3/06 [50] Field of Search..219/22l-242, 243; 219/221, 226, 222, 227, 236-239, 533, 531; 16/1 16;30/140; 228/5155; 132/33 [56] References Cited UNITED STATES PATENTS2,031,532 2/1936 Goldman 219/239 2,257,376 9/1941 Grey 219/238X PrimaryExaminer-A. Bartis Attorney-Scofield, Kokjer, Scofield and LoweABSTRACT: A hair-curling instrument embodies a heat conductive shellwhich is internally heated by an electric heating element and which issupported from a hollow handle by means of an arrangement which inhibitsthe transfer of heat from the heating element to the handle. A tubularrivet extending through an aperture in an end closure on the shell andan opening in the end of the handle holds the handle and-shell in axialalignment. The heating element leads pass through the rivet. Thermallynonconductive spacers secured to the handle end and seated in recessesin the shell end closure are interposed between the shell closure andthe handle end so as to define air gap between the confronting surfacesof the handle end and the closure member.

P te ted m 18, 1911 INVENTQR flamue/ L. Man/m ELECTRICALLY HEATEDHAIR-CURLING INSTRUMENT BACKGROUND OF THE INVENTION The curling of hairthrough the use of heat is an ancient art. Up until quite recent times,it had fallen out of vogue as a means of curling other than atprofessional salons, due principally to the complexity of equipment anddesire to save time. Instead, the cold wave kit became the most utilizedform of home hair treatment.

As noted above, both costly equipment and the time required to obtain asatisfactory curl have posed problems'in promoting widespread homecurling with the heated curlers. Recent developments in the field have,however, resulted in a trend back toward the use of heat. See, forexample, the U.S. Pat. to McNair, Nos. 3,250,895 and 3,283,122, whichdeal with quick heating heat transfer units which are operable toprovide the heat necessary for curling and are convenient to use athome.

While devices such as mentioned above were a great improvement, still aproblem which has long plagued manufacturers of curling irons and thelike is one of obtaining a hot iron" while preventing the handle frombecoming so hot that it is uncomfortable to hold or worse, eitherdamages the holder or is itself damaged. In most cases, this has beensolved, if at all, by reducing the temperature to which the ironl'orheating unit is heated, or alternatively,through employment of expensiveinsulating constructions for protecting the handle. The use of lowerheats has the drawback'thatit takes longer to achieve the curl and, ofcourse, the drawback as tothe utilization of expensive instrumentconstruction is that it becomes unavailable to the average consumer.

SUMMARY OF THE INVENTION The present invention derived from an effortto-provide a low-cost, lightweight, portable'electric heating unit foruse in conjunction with hair-curling rolls like those disclosed intheaforesaid McNair patents and which would be capable of being heldcomfortably while still putting out heat at a greater rate than inconventional instruments. To this end, Iconceived a construction whichembodies a'heat conductive shell which is internally heated by anelectric heating element and which is supported from a handle bymeans ofa support arrangement which effectively inhibits heat transfer from theheating element to the handle through a combination-of limiting the rateof and pathways open to direct conduction and providing for convectiondissipation of heat at the interface between the handle and heattransfer unit. All this is achieved while still obtaining optimumutilization of the heat supplied bythe heating element.

A hair-curling instrument according to my invention has additionaladvantages in that it is light and easy to handle, can be manufacturedand assembled with relative ease and at low cost (considering thebenefits gained) and can be made quite attractive in appearance.

Other objects and advantages of devices embodying the invention willappear in the course of the following description.

DETAILED DESCRIPTION in the accompanying drawing, which forms a part ofthe specification and is to be read in conjunction therewith, and inwhich like reference numerals indicate like parts in thevarious views;

FIG. 1 is an elevational view of a preferred form of the hair curlinginstrument embodying the invention;

FIG. 2 is a sectional view taken along the line2-2 of FIG. 1 in thedirection of the arrows;

FIG. 3 is a perspective view showing the component parts absent theheating unit shell in exploded relationship;

FIG. 4 is an end'view of the handle-mounted heat barrier element;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4 in thedirection of the arrows; and

FIG. 6 is a perspective view showing the heat unit closure member in aninverted position from that illustrated in FIG. 3.

Referring now to the drawing and initially to FIGS. 1 and 2, the basiccomponents of the preferred instrument illustrated therein comprise ahandle 10 and a heat transfer unit 11 which is connected to andsupported from one end of the handle. As seen in FIG. 2, the handle 10has a recessed free end 10a in which are supported two electric terminalprongs 13 by which the implement may be connected with the plug (notshown) of a conventional electric cord leading to a source of electricalenergy.

The heat transfer unit 11 includes a hollow cylindrical shell 14 havingthe upper or outer closed end 15. Preferably, the shell is composed ofaluminum or other material having good heat conductivity.

Positioned interiorly of the shell is an electric heating element whichcomprises the heat-resistant plate member 16 on which, is wrapped orwound an electric resistance heating wire 17. The width of the plate 16is such that it fits easily within the interior of the shell 14. x

The ends of the resistance wire 17 are respectively connected with ashort conductor 18 and a longer conductor wire 19. The wire 18 is inturn electrically connected with an electrically nonconductive basemember 20 which forms the base of a thermostatic switch having thebimetal thermal element 21. The thennal element operates to open andclose a contact at 22 in response to predetermined temperature limits.The fixed end of the bimetal element is connected with a contact at 23and this contact is in turn connected with another conductor 24. v

The open lower end of the shell 14 is closed by means of a pluglikeclosure member 25 which fits telescopically within .the end of the shelland which is composed of metal. The rim of the member 25 is providedwith a circumferential groove 26. The shell is joined with the closure25 by striking metal segments 14a into the groove at at least two pointsaround the shell. The closure member is positioned properly within theshell by means of an end flange 27 which provides a shoulder which seatsagainst the confronting end edge of the shell.

The closure member 25 is provided with a central aperture 25a. Receivedthrough this aperture and extending well beyond the closure member isthe barrel portion 29 of a hollow rivet having the flanged head 29awhich seats on the inside end of the closure member. The electric leads19 and 24,

which incidentally are thermally insulated, exit from the shell 14through the axis of the rivet 29.

The heating unit 11 is completed by inclusion on the interior of shell14 at the upper end of ceramic heat storage elements 30 which are pressfitted into the interior of the shell.

The handle 10 includes the main handle portion 12-which may be made ofany satisfactory plastic such as, for example, a molded high densitypolyethylene. The handle may be given any'shape comfortable to the hand.The handle illustrated is a hollow handle having the relatively largehead portion 12a which is formed internally with a counterbore 12bdefining an annular shoulder 120.

Press fitted within the counterbore 12b is an inverted cupshaped endmember 31. This member is constructed of a material having. an extremelyhigh resistance both to conductivity of and destruction by heat.Preferably, it is molded from a phenolic resin. While its form may vary,it has in the illustrated embodiment, a cylindrical skirt portion 31awhich is slotted longitudinally at 31b in order to permit the necessaryresilient flexing of the skirt for press fitting the end member into theend bore of the handle. The skirt depends from a web portion 31c whichis centrally apertured at 31d to permit the passage therethrough of therivet barrel 29 with the contained electric leads. The rivet is, ofcourse, headed as at 29b on the underside of the web 31c to join thecomponents 10 and 11 together.

Formed on the outer face of the web 310 of the handle end member are aplurality (in the illustrated embodiment, four) of spaced posts 31f. Theposts are equiangularly spaced around the center of the end member. Theposts are formed integrally with the end member.

The posts are of sufficient length to insure that when engaged with theoutside face of the end closure 25 on the heat unit 11, the surface ofthe end closure will be spaced at all the points from any portion of thehandle 10. Consequently, the posts serve to form a substantial air gapbetween the heat unit 11 and the handle through which air is free tocirculate and from which convection currents can readily escape.

The posts also serve, as part of the connecting means between the handleand heat transfer unit 11, to insure against twisting displacement ofone component relative to the other. As can be best seen in FIG. 6, theoutside, or under, face of the closure member 25 of the heat transferunit is provided with a plurality of shallow cavities or recesses whichare located to register respectively with the ends of the posts 31 f.The post ends seat within these recesses and obviously any twisting ofthe heat transfer unit 11 relative to the handle 10 is effectivelyresisted.

To aid in maintaining the handle end member 31 within the receptacle,the surface of the counterbore 12b of the handle is provided near theouter end of the counterbore with a plurality of bosses or lips 12d. Theoverall length of the handle end insert member 31 is made such that wheninserted to its seating depth, the upper or outer edge of the insertwill be inside the lips. The material of which the handle is constructedis significantly flexible and resilient as to permit the lips 12d togive during insertion of the member 31, after which they will return tothe projecting position and serve as lugs limiting outward displacementof the member.

From the foregoing, it will be evident that l have achieved all of theobjects and advantages hereinbefore set forth. The stand off arrangementwhich separates the heated portions of the heating unit lll from contactwith the handle 10 limits greatly the direct conductively of heat. Theonly pathways open to direct conduction are the posts 3lfand the verysmall cross-sectional area provided by the barrel of the rivet 29. Sincethe posts 31f are made of thermally nonconductive material, they providevery little, if any, conductivity. In addition, the air space providedbetween the two units through the construction described permits ofready dissipation of heat liberated at the outer surface of the plug 25.The normal and natural motions of the operator in handling the unit willassure of continuous dissipation of heat by convection and circulationfrom the zone between the heating unit and handle.

it will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawing is to beinterpreted as illustrative and not in a limiting sense.

lclaim:

l. A hair-curling heating instrument comprising:

a hollow heat conductive shell,

a heat-conducting closure member closing one end of said shell,

a heating element within the shell having electric leads which exit fromthe shell through an aperture in said closure member,

a hollow handle having a closed end, said handle positioned with itssaid end confronting said end closure member of said shell, said leadsextending into said handle through an opening in said handle end,

a tubular rivet extending through the aperture and opening respectivelyon said closure member and handle end and holding said handle and shellin axial alignment, said leads passing through said rivet, and

thermally nonconductive spacer means interposed between said shellclosure member and handle end so constructed and positioned as to definea substantial air ap between the ma or confronting surfaces of said hanle end and

1. A hair-curling heating instrument comprising: a hollow heatconductive shell, a heat-conducting closure member closing one end ofsaid shell, a heating element within the shell having electric leadswhich exit from the shell through an aperture in said closure member, ahollow handle having a closed end, said handle positioned with its saidend confronting said end closure member of said shell, said leadsextending into said handle through an opening in said handle end, atubular rivet extending through the aperture and opening respectively onsaid closure member and handle end and holding said handle and shell inaxial alignment, said leads passing through said rivet, and thermallynonconductive spacer means interposed between said shell closure memberand handle end so constructed and positioned as to define a substantialair gap between the major confronting surfaces of said handle end andclosure member for free air circulation therebetween, said spacer meanssecured to sad handle end and having end portions seated in recesses insaid shell closure member to prevent said handle member and closuremember from twisting relative to one another.